Synthetic fibrous product and process of making the same



e. H. ELLIS 2,134,659 SYNTHETIC FIBROUS PRODUCT AND PROCESS OF MAKING THE SAME Filed Jan. 13, 1954 Invenior- Geonoel-LElZis Patented Oct. 25,1938

UNITED STATES PATENT OFF-ICE SYNTHETIC FIBROUS PRODUCT AND I PROCESS MAKING THE SAME George H. Ellis, St. Paul, Minn., assignor to The 'Insulite Company, Minneapolis, Minn, a corporation of Minnesota ApplicationJanuai-y 13, 1934, Serial No. 706,556

11 Claims.

" struction of buildings and for various other purposes.

A further, object an improved method of forming composition boards or sheets from fibrous pulp stock which consists in subjecting the fibrous pulp stock to rotating elements to form a web," subjecting the web to pressure to remove surplus fluid, applying heat and pressure to compact and unite the fibrous web, severing the web transversely and 20 subjecting the severed portions to cooling.

A further object of the "invention is the production of synthetic bodies which are evenly col-' ored and of uniform thickness.

A further object of the invention is the continuous production of a sheet of the type described in any length, width and thickness.

The invention relates to the production of hard, stifi bodies by first forming from fibrous pulp stock a continuous web or sheet, squeezing the surplus moisture from the web or sheet, passing the web through heated rolls to compact and unite the web into a homogeneous body, trimming or severing the sheet longitudinally, severing the sheet transversely, passing the severed portion through humidifying and cooling chamhers-from which the finished product is removed.

The invention also relates to production of an endless sheet from fibrous pulp stock, removing the surplus moisture from the sheet, passing the web or sheet through rolls to dry, compact and unite thefibrous sheet into a hard, still, water resistant body, severing the body into the desired length and Width, passing the severed portions through treating chambers to complete the operation.

The -invention also relates to fibrous products and method of making the same which will not be attacked by insects, fungi or-the like.

-In carrying out the process water proofing material may be added to the fibrous pulp so that the finished products will have greater water resistant qualities. The water proofing material may be either vegetable or mineral oils. The water resistant material is preferably mixed with fibrous pulp stock but it may be added after the of the-invention is to provide (on. sa-zi) sheet is formed and so far as the synthetic product or the method of making the same is concerned it is not material at what time the water resistant material is added.

A still further object of the invention is to provide an improved method by which synthetic bodies may be produced eflicientiy, economically and continuously.

If deslred,-the hard and compact sheet may be tempered and the tempering material may be forced into'the sheet by the use of heated rolls but it is to be understood that tempering may be done without the use of heated rolls although it has been found preferable to use such rolls.

With the foregoing and other objects in view the invention consists in new synthetic products and the novel steps of the method of making the same herein-after to be more fully described but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the claims hereunto appended. In the accompanying drawing which 11- lustrates one embodiment of the invention and forms a part of the specification: Figure 1 is a view of a diagrammatically illustrated apparatus for making boards or sheets and includes a felting machine, a pressing means, a cutting device, a humidifying and a cooling means.

Figure 2 is a sectional view of the rotative pressing members showing a fibrous sheet passing there-through. To fully understand the advantages of the novel steps of the process as well as the new products references will be made to the method and the product heretofore used and made. In the known methods of making the synthetic products which are hard and stifl, it has been found necessary to sever the wet sheet into sections and to place su'chsevered sections in a heated hydraulic press where they are subjected to heat and pressure for a period ranging from 14 to 30 minutes. The size of the sheets produced is of a necessity limited to the size of the hydraulic press. According to the method hereinafter to be more fully described the fibrous' sheet after being formed is passed through one or morepairs of heated rolls which compacts, unites and causes the fibers to cohere into a homogeneous mass. The sheet this produced can be severed into any dimensions desired. The synthetic product of the character mentioned is thus produced rapidly and the qualities of the product as to tensile strength. uniformity of thickness and water resistance is far superior to any heretofore produced.

In making the synthetic products from fibrous vegetable material, preferably wood, the fibrous material is mechanically disintegrated or fiberized into long, coarse fibers such as are commonly used in the manufacture of insulating bodies. Although it is preferred that mechanically disintegrated fiibrous material be used, highly satisfactory results have been obtained by the use of semi-chemical pulp or a mixture of mechanical and semi-chemical pulp.

It has been found to be highly desirable that some binder be co-mingled with the pulp before the fibrous sheet is formed. Also, iian insect and fungi proof synthetic product is desired some toxic agent should be thoroughly co-mingled with the pulp stock, or introduced into the formed sheet prior to the pressing. The toxic agent if co-mingled with the pulp or added to the wet sheet after being formed by vacuum means as shown in my copending application, Serial No. 706,555, filed January 13, 1934, now Patent 2,030,625, will be thoroughly distributed through the finished product. It is preferred that the toxic agent be a coal tar product which is not poisonous to human beings but any suitable metallic salts may also be used as desired.

The fibrous pulp is formed into relatively thick sheets depending upon the thickness of the finished product desired'and the sheet so formed is subjected to a squeezing device to remove the surplus water. The sheet after it has been subiected to this action is passed through compacting rolls in a substantially wet condition.

In Figure 1 there is illustrated an arrangement of apparatus for producing the improved synthetic bodies and for carrying out the novel process. This apparatus is shown comprising a suitable felting machine A, pressing or squeezing device B, pre-heating means "0, rotatable pressing means D, liquid spreading rolls E, heated rolls 1'', longitudinal cutting means (3, transversely severing means H, humidifying chamber I, and cooling chamber J.

vals by means of cutting device H. The severed portions are then, passed horizontally into a humidifying chamber where they are treated so that the tendency to warp is reduced to a minimum. From the humidifying chamber the severed portions pass through a cooling device where they are thoroughly cooled and when discharged from this device are ready for shipment. The sheet and the severed portions are caused to be advanced from the forming machine to thetlme they are discharged from the cooling chamber by means of positively driven rolls I0, endless conveyer or by any other suitable means.

In producingsynthetic products of the character mentioned it is desired that the moisture contents of the finished product be as high as 5 to 9% as a board which contains less moisture than this when exposed to atmosphericair of ordinary humidity has a tendency to absorb moisture therefrom.

Synthetic products absorb very little moisture when stored in a warehouse or the like and when stored such bodies normally preserve their shape. When synthetic bodies are secured in position, for example on a wall and fully exposed to atmospheric air they absorb moisture therefrom and sometimes buckle or warp. Although in some instances the synthetic bodies will buckle or warp when not secured in position, normally warping or buckling of synthetic products is due to the fact that after being secured in place they absorb moisture that causes them to expand and being so secured in place the expansion is The felting machine here shown comprises a suitable tank 2, into which fibrous pulp stock is delivered from a suitable means, not shown. The pulp is deposited on the surface of and fed upwardly between cylinders 3 and l and is thus formed into a web or sheet 5, which then passes through the pressing or squeezing device B, to remove the surplus liquid or water. The sheet may, if desired, be passed through a pre-heating means and then passed between the heated pressing rolls where it is dried. compacted. hardened and united into a homogeneous body.

The surfaces of, the rotative pressing means are maintained in a polished and clean condition by means of roll I, a screen I is operatively mounted on rolls 9 and extends around the lower pressing elements. If a smooth surface is desired on both sides of the finished product the screen is not used.

The sheet after leaving the pressing means passes between rolls E, which are so. mounted and arranged that they spread upon the surface of the sheet a liquid for the purpose of tempering the sheet. The sheet is then passed through the heated rolls F, to evenly distribute over the surface of the sheet the tempered material and to cause the tempering material to penetrate the body of the sheet. The hard tempered sheet is then trimmed or cut longitudinally and thereafter the sheet is transversely'ievered at interrestricted to a certain extent and this results in what is commonly known as warping.

There have been many efforts heretofore made to produce a non-warpable synthetic product but such efforts have proved extremely difilcult to carry out or highly unsatisfactory. When synthetic products are treated according to the process herein described the tendency ofsuch products to warp is reduced to a minimum. 7

The pressing rolls E, may be of any desired size and highly satisfactory results have thus far been obtained by using rolls in diameter and also rolls in diameter. The pressing rolls should be heated to a temperature ranging from 300 to If. The temperature at which the rolls are heated depends in part upon the speed at which the rolls are to be rotated, upon the qualities of the board desired and upon the pressure to which the sheet being pressedis subjected. The uniformity of color of the synthetic bodies also depends upon maintaining the pressing temperature substantially constant.

To obtain different thicknesses and to insure uniform thickness of the sheet means are provided for adjustably spacing the rolls at a predetermined distance apart. This means may be mounted directly upon the rolls themselves or it may be a separate .unit.

In Figure 2 is disclosed the action of the pressing rolls upon the fibrous sheet as well as one means for heating the rolls. The relatively thick fibrous sheet as it passes between the pressing rolls is gradually compacted into the predetermined thickness and the simultaneous application of heat and pressure causes the fibrous material 'to coalesce and become welded together so as form a homogeneous body.

The exact action that takes place while the sheetispassingthroughthepressrolisisnot known but the products produced are far superior to the products produced by a hydraulic press. Thllilinpartduetothefactthat simm- 1 The pressing rolls may be heated by gas burners ll, as shown in Figure 2, wherein the flames impinge. directly against the inner surfaces of the rolls. The rolls may as readily be heated by oil burners or by electrical'means.

depends upon the desired density of the finished product. Pressures from 10,000 to 50,000- pounds per foot of width of sheet being pressed give very satisfactory results but variations in pressure above and below these amounts may be resorted to if desired.

The sheet after passing through the pressing rolls may be severed into the desired length but it is preferred that the sheet be passed'through rolls where tempering material such as gloss oil is applied to the hot sheet and to complete the tempering operation the sheet is passed through heated rolls which causes the tempering material topenetrate entirely through thesheet.

The sheet is then divided, passed into a humidiiier and thence-through a cooling means. The humidifying and cooling steps may be reversed, that is, the synthetic bodies may be first cooled and then humidified but it is preferred that the bodies be humidified when they are in a relatively hot condition as the time for humidifying when so treatedis greatly reduced.

It has been discovered that under certain conditions some vegetable oils and under other conditions some mineral oils when subjected to the action of pressing members rotating at a suitable speed and heated to a suitable temperature, hardens, oxidizes or vulcanizes. This action, whatever may be the true explanation, is taken advantage of to obtain synthetic products having I increased tensile strength, hardness and water resistance.

Depending upon the qualities of the synthetic bodies desired, vegetable oil, such as soy bean oil, tung oil, cotton seed oil or the like or a mineral oil, such as petrolatum or the like is thoroughly coinrningled with the fibrous stock. The amount -'of oil used varies from 1 to 10% of the dried weight of the finished product. ,The sheet when formed from the pulp stock'will have the oil thoroughly disseminated there-through. This sheetis then subjected to some means for reducing the water contents to say about 50%. The sheet is then preferably passed through a pro-heating means to raise thetemperature'thereof so that when the sheet when delivered to the pressing I screen isused around the lower and/or upper press rolls but if a smooth flnishis desired on the surfaces of the synthetic products screened members are not used. The sheet after being discharged from the heated pressing rolls is subjected to tempering operation to increase certain qualities, particularly the hardness of the syntheticproducts. The sheet is then severed to any desired dimension and passed through a humidifying chamber which is preferably a steam chamher and thence to a cooling means. ferred construction of the cooling means is pro- The previded with forced circulation so as to reduce the time required for cooling the synthetic products. The synthetic bodies produced by this method are hard, grainless, homogeneous, of uniform color and thickness and the tendency to warp is reduced to a minimum. It is to be understood that certain steps of the process may be altered as to The pressure to which the sheet is subjected the sequence in which they are performedand that certain steps may be omitted and that the and coalesces the synthetic products into a homogeneous body ofuniform thickness.

If desired, the oil that has been incorporated in the sheet may be utilized whollyfortempering and if so used it is not necessary to add tempering material to the. surface but it has been found highly desirable that the.oil be commingled with the pulp and the tempering material spread over the surface of the pressed sheet in. a manner heretofore described. I

Having thus described the invention what I claim is: l i

. 1. A method of producing synthetic bodies which comprises forming a sheet from vegetable fibrous pulp stock passing the sheet through heating means to raise the temperature of the sheet without substantially decreasing the amount of water in the sheet, compacting the sheet into a homogeneous body by means of heated pressing rolls, and transversely severing the sheet.

2. A continuous method of producing hard, water resistant bodies which comprises forming a sheet of material from vegetable flbrous' pulp stock, raising the temperature of the sheet, passing the wet sheet through heated pressing rolls todry, compact and unite the sheet into a homogeneous body, severing the sheet transversely and cooling severed portions.

3. A method of producing hard, water resistant and insecticide proof, synthetic bodies which comprises forming a sheet from fibrous pulp stock in sure to a wet, fibrous board. rolls will not unduly reduce the temperature of such rolls. It is preferred that when the sheet is 5. A method of producing a hard, water-resisting board which comprises the steps of forming relatively thick board from long, raw, coarse,

vegetable fibers and a binder that hardens under heat and pressure, heating the board, continuous- 1y advancing the moist board in a substantially horizontal plane, simultaneously applying heat and pressure to the board by means of rotatable members, and cooling the board.

, 6. A hard, dense, high tensile strength board having at least one major face smooth and great water-resisting properties, resulting from the simultaneous application'of heat and pressure within the ranges herein described, to the raw pulp board having a high-moisture content containing a binder, that hardens under heat and pressure and a toxic agent, said binder being present within the ranges herein set forth.

7. A- method of manufacturing hard, stiff,

waterboard which comprises forming a board from vegetable fibrous pulp stock in a water bath, removing the surplus moisture, continuously advancing the wet board in a substantially straight line and simultaneously applying heat and pressure to the board while being advanced.

8. A method of manufacturing substantiallypermanent gauge dimension board and the like,

comprising forming a product from vegetable fibrous pulp stock having commingled therewith a drying vegetable oil and containing substantially all the original natural cementing materials of the original fibrous material, heating the product to raise the temperature of the moisture contents, subjecting the hot product, moist throughout, to simultaneous application of heat and pressure, and continuously advancing the product while applying heat and pressure.

9. A continuous process of manufacturing hard, stifi, water-resisting board-like products-which consists of mixing an oil of the class described within the range set forth; with pulpy vegetable material in a water bath, said pulpy materials containing substantially all the original natural cementing materials of the original material from which the pulp is produced; manipulating the mass to form a product; heating the product; subjecting the wet product while being continuously advanced to simultaneous application. of

'heat and pressure by rotatable members, and

cooling the product.

10. A panel board consisting of a hard, dense, homogeneous product with at least one major face smooth and highly water resistant, produced from sheeted vegetable fibrous material containing substantially all the natural cementing materials oi the original fibrous material, a waterproofing material that hardens under heat and pressure in the sheeted material, bonded and compacted and the water-proofing material hardened by simultaneous application or heat and pressure to the wet sheeted material, and subsequently having water-prooflng'material spread on at least one major face and forced into the board 

